Back-tube-sheet structure.



A. RI HODGES.

BACK TUBE SHEET STRUCTURE.

APPucATloN man ma. 23. |911.

Patented Jan. 28, 1919.

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A. R. HODGES.

BACK TUBE SHEET STRUCTURE.

APPLICATION FILED IEB. 23. I9II.

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ALLAN n. HoDGEs, or

MEMPHIS, TENNESSEE, ASSIGNOR 0F ONE-HALF TO CYRUS A.

MCALLISTER, OF MEMPHIS, TENNESSEE.

BACK-TUBE-SHEET STRUCTURE.

Specification of Letters Patent.

Patented Jan. 28, 1919.

Application led February 23, 1917. Serial No. 150,513.

To all whom it may concern:

Be it known that I, ALLAN R. HoDGEs, a citizen of the United States,residing at Memphis, in the county of Shelby and State of Tennessee,have invented new and useful Improvements in Back-Tube-Sheet Structures,of which the following is a specification.

This invention relates to an improved back tube sheet structure forlocomotive boilers.

The principal objects of the invention are to providea structure wherebythe back tube sheet will not be destructively or detrimentally affectedby the stresses developed in consequence of the contraction andexpansion Vof the re-box shell, nor by the stresses developed :by itsown expansion and contraction in consequence of heat; to provide astructure wherein the integrity of the connections between the tube endsand the back tube sheet will not be affected by the stresses developedincident t0 the expansion and contraction of the re-box shell; and toprovide a simple and improved structural relation between the back tubesheet and the front end of the fire-box shell whereby the riveted seamby which the jointure of the back tube sheet to the shell is effected isso located that it receives efficient protection against the heat to.which the back tube sheet is subjected, and whereby other importantadvantages are secured.

A further object of the invention is to provide a back tube sheetstructure whereby the back tube sheet may be removed and renewedwithcomparative ease and without thenecessity in existing boilerconstructions of the type where the shells are braced by stay sheets ofseparating the outer shell from the locomotive barrel and disconnectingthe foremost stay sheet from the outer shell and fire-box shell. l

With the above objects in view, the invention consists in certainfeatures of structure and structural l combination involving the frontend of the fire-box shell. the back tube sheet and the jointure of saidsheet to said shell.` More particularly, the invention consists in theprovision, as a functional part of the {ire-box shell at the front endthereof, of a. exible channeled frame to which the back tube sheet issecured and which is specially constructed and arranged to act, withreference to said tube sheet and shell, re-

spectively, in taking up and equalizing the stresses developed by theradial and longitudinal expansion and contraction of the lire-box shelland the radial expansion and contraction of the back tube sheet, tomaintain the maximum rigidity of the tube sheet while permitting itsexpansion in consequence of heat, and to prevent the transmission ofdestructive stresses from the re-box shell to the tube sheet or viceversa; and in the novel relation between the said channel and the tubesheet.

What is now considered as a preferred embodiment of the invention isillustrated in the accompanying drawings, wherein Figure 1 is across-sectional view on the line 1-1 of Fig. 2, looking in the directionof the arrow;

Fig. 2 is a fragmentary longitudinal scction of a locomotive boilershowing details of the back tube sheet structure;

Fig, 3 is a face elevation and Fig. 4 is a side elevation showing afieXible joint which constitutes a structural element of a stay sheetwith which the above-mentioned channel and frame may be combined;

Fig. 5 is a side elevation illustrating the manner of articulating theelements of the {iexible joint; and

Figs. 6, 7 and 8 are, respectively, plan, side and end elevations of oneof the elements of the exible joint.

Similar characters of reference designate corresponding parts throughoutthe several views.

The improved back tube sheet structure is applicable to any type oflocomotive boiler. The boiler shown is of the Jacobs- Shupert typewherein `thc fire-box shell 1 and outer shell 2 are made of channeledsections 3 and 4, respectively, which are braced to one another by staysheets 5 Nvhose marginal portions are held between the flanges of theadjoining channeled sections and secured by the rivets 6 which connectsaid flanges. The stay sheets 5 and sling stays 5l may be of anysuitable construction. but, as shown` are of the construction whichforms the subject 0f my co-pending application Serial No. 150,512. p

According to the present invention, the fire-box shell has at its frontend as a part thereof. and also as a part of the improved back tubesheet structure, a frame 7 whose lineal outline conforms te the outlinecf the back tube sheet 8, as dictated by the ordinaryl The frame 7constitutes, in functional ef fect, the extreme front section of thefireboxshell andit has ,a substantially U-shaped cross-section Iandthereby provides a channel which opens outwardly in thetransverse or.

radial plane of the boiler. The said channelhas a bow or base portion 10of regularly curved, preferably semi-circular, cross-section and rearand front side walls l1 and 12 which are lcontinued in parallel relationin planes transverse to the boiler through a suitable extent, z'. e. anextent sulicient -to provide suitably wide bearing surfaces alongl theseams formed by the riveting of the frame 7 to the adjacent parts.

The frame 7 is integrally combined with and projects forward from theinner throat sheet 13; said frame is, preferably, also integrallycombined with the foremost stay sheet'; and the straight or flat channelside wall 11 merges with, and becomes in fact part of, saidl stay `sheetand throat sheet. Where the 'frame'7 is thus formed in combination withthe vstay sheet and inner throat sheet, said frame is secured directlyto the foremost section 3 ofthe nre-box shell 1 as by rivets 14 whichpass through the channel side wall 11 and the adjacent flange of thesaid section 3, the lines of riveting being continued downward at thesides of the stay sheet in the lportions thereof below the sides oftheframe 7.

The back tube sheet 8 consists of a flat plate of boiler 'steel ofsuitable gage whose marginal portion is extended sufliciently beyond thetubes 9 to come lflush with the edge of the channel side wall 12; andthe said extended marginal portion of the tube sheet 8 is secured toythe said wall`12, at close and regular intervals, throughout itsextent, by rivets 15. The tube sheet 8 is supported by the frame 7 andat its lowest point is braced to the barrel of 'the locomotive by asuitable belly brace 8a which is preferably of flexible construction andincludes sections connected b'y `a flexible inter-engaging hook joint ofthe general character to be `hereafter described inconnection with thestatement of the details, of the stay sheet. j

It is to be observed ythat, the marginal portion of the sheet 8 and theliat channel side wall 12 have a uniform and lcol'nparatively wide'bearing againstlone another to promote the security o'fv'theirysteam-tight jointure. It is also to'be observed that the seam or jointbetween the framel and the back tube sheet 8 and the circle of rivets 15by which 'said seam lor joint is completed are located outside o'f thelire-box, remote from lthe flames and direct heat, and within the steamspacev 16 of the boiler whereby the said joint and its rivetvconnections will be at all times submerged in the water nsaid steamspace and will be most efhciently protected against the direct heat ofvthe lire-box and against the heat latentinthe back tube sheet and frame7 .Y The side wall 12 is located in the plane to vthe circulation ofwater nor to the free removal of scale and mud deposits.

rlhe stay sheet 5 inthe special construc tion thereof shown, consists ofan arch member 17 which is secured to they fire-box shell 1, an archmember 18 which is secured tothe outer shell 2, and a series of radiallydisposed llexible joints 19 between the said members 17 and 18, eachconsisting `of interengaging hooks 20 formed at the ends of companionradial fingers 21 with which 'said members are provided, each hookhaving aterminal lug 22 for which the companion hook has an opening 23.The arch member 18 is made in sections which are individually secured tothe arch vmember 17 after the latter has been connected to the fire-boxshell, the organization of the member 7v and the sections of the member18 involving an initial transverse movement of the hooks 20 to aline the'terminal lugs 22 with the openings 23, as shown in F ig. 5, and asubsequent longitudinal movement of said hooks to insert the terminallugs 22 through the openings l/Vhen thus organized, bracing web'sorbridges 211 are secured by `welding between the lugs 22 and the fingers21 towardwhich said vlugs point, as shown in Figs. '3 and 4. p

A stay sheet of theV construction disclosed, while not obligatory inconnection with 'the back tube sheet struct-ure `which constitutes theinvention, is ofspecial advantage in'that its augmented flexibility, dueto the loose play provided for by the joints 19, is effective 'inrelieving the fire-box shell, and 'with it the frame 7, of severe andvdestructive stresses to which the A'said shell is subject Iinlocomotive "boilers of the heretofore existing t es. i

yllhe frame l7 by Virtuevof itsfchanneled or `U -s'hap ed cross section'and the 'regular 'curvavture of the channel base 1Q, and also by virtue'of its inherent ducti1ity,'h`a"s pronounced flexibility which isvadv'a'nt'ageouslj f "utilized in connection with 'the arrangement ofy'said frame relatively to the back *tubeA sheet whereby, without injuryto itself, said frame may yield `o1" stretch in the longitudinaldirection kof the boiler and either 'of its side walls 11 or l2 may beindependently stretched or compressed vin 'the directions of theirplanes, i. e. in the transverse or radial direction of the boiler,without impairing the stability of the form of the back tube sheet orthe integrity of the connections between it and the tube ends. Inconsequence of such flexibility, the stresses incident to the radial andlongitudinal expansion and contraction of the fire-box shell will, atthe front of the fire-box, be substantially absorbed and equalized bythe frame 7 and will not be transmitted, at least to any detrimentalextent, to the back tube sheet 8; and in like manner, the stresses inconnection with the expansion and contraction of the back tube sheet 8,as by changes in temperature, will be relieved or taken up and equalizedby the frame 7 and will not be transmitted to the fire-box shell.

An important advantage of the structure disclosed is the facility withwhich the back tube sheet may be removed when unit for further use and anew one substituted. In such a case, after the tube ends have been freedfrom the back tube sheet the securing rivets 15 of the latter are cutand the sheet, by canting it obliquely, is inserted rearwardly throughthe frame 7 and removed from the boiler at the rear end thereof. On suchremoval of the back tube .sheet the frame 7 is left intact and a newsheet, introduced through the rear end of the boiler and insertedforwardly through said frame, is secured in the manner disclosed to thefront channel wall 12, after which the ends of the tubes 9 are fitted inthe new sheet. These operations do not require the separation of theouter shell from the locomotive barrel and the removal of the foremoststay sheet from the shells as is necessary in existing boilerconstructions where stay sheets are employed to brace the two shells.

In connection with the above noted advantage it may be observed that theframe 7,

Copies of this patent may be obtained for ve cents each, by addressingthe in the construction disclosed, will serve at least as long as thefire-box of which it forms an element and, therefore, will outlast theback tube sheet and serve in connection with all necessary renewals ofsuch sheets.

I claim as my invention- In a back tube sheet structure for locomotiveboilers, in combination, aback tube sheet, a throat sheet at the frontend of the firebox shell and forming the rear wall of the front waterleg and a frame at the front end of the firebox shell and which supportssaid tube sheet and forms a functional element of said shell, said frameconforming in lineal outline to the tube sheet and having a U-shapedcross section to provide a channel which opens outward in the radial ortransverse plane of the boiler and has a semi-circular base and parallelside walls projecting from said base, the rear side wall of said channelbeing secured to the irebox shell and being formed integrally with saidthroat sheet and the front side wall of said channel being secured tothe marginal portion of the tube sheet, the seam at the jointure of saidfront side wall and said tube sheet being located in the plane of saidwater leg and the submerged lower portion of said seam being locatedjust above the water leg and somewhat in the rear of the locomotivebarrel, the frame and tube sheet having such outline that the tubesheet, in renewal, may be inserted, in planary form, through the openingof the frame.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

ALLAN R. HODGES. Witnesses:

JULIUS Powers, J oHN L. FLETCHER.

Commissioner of Patents,

Washington, D. C.

